Shadow treasurer Chris Bowen believes the federal budget needs more than a bit of tinkering in next month's mid-year review.
While Prime Minister Tony Abbott thinks the government can get back on track by removing a few policy "barnacles", Mr Bowen argues it needs to go back to the drawing board and start again.
"The barnacles aren't the problem, the budget is the problem," he told ABC radio on Wednesday.
Greens deputy leader Adam Bandt said reports the government is considering ditching its proposed $7 GP co-payment wasn't just "scraping barnacles off the hull".
"The ship's going down," he told reporters in Canberra.
The prime minister's parliamentary secretary Josh Frydenberg conceded the budget had hit some "road blocks" in the Senate.
"But we continue to negotiate with the independents and the cross benchers because we believe these reforms are both important and necessary," he said.
Nationals MP Andrew Broad said the government was given the task of making hard decisions to get the country back on track.
"I think if we look at (the budget) in its entirety it was actually a lot fairer than people made out," he said.
The Organisation for Economic Co-operation and Development has warned the government not to be heavy-handed in cutting the budget in the near term.
"Given economic uncertainties, it should avoid heavy front loading," it said in its latest Economic Outlook released in Paris on Tuesday.
